6 crayons cost $6.18. Which equation would help determine the cost of 3 crayons?
There are several equations that could help determine the cost, each with a slightly different approach. Let $x$ represent the unknown cost of 3 crayons. Since 3 crayons cost $x$ , we have the following proportion: $\dfrac{3}{x}$ We can write the fact that 6 crayons cost $6.18 as a proportion: $\dfrac{6}{\$6.18}$ The cost changes along with the number of crayons purchased, and so the two proportions are equivalent. $\dfrac{3}{x} = \dfrac{6}{\$6.18}$